Kindly explain how to calculate the Initial Surface Absorption Test (ISAT) of concrete?
The initial surface absorption is then simply the number of scale units moved in 1 minute. If readings are taken for a longer or shorter period they must be converted to 1 minute duration.
Before use the capillary tube is calibrated to determine the area of the cross section. The area of the cell is measured and the scale factor for the cell/tube combination is determined.
0.01 ml/m3/sec = 6.10-4 AreaCell length mm of tubing Areacapillary
For initial surface absorption test calculation may be as follows:
ISATt = Nt x Cf
Where ISATt = Initial surface absorption t minutes after water first touched concrete surface.
Nt= Number of scale divisions moved, in a minute, t minutes after water first touched
concrete surface.
Cf= Calibration factor of capillary tube determined in accordance with BS 1881- 208.
The ISAT can also be calculated from first principles
ISAT = length. Atube .10 (where t is in seconds)
Acell .t Atube and Acell are in mm5, length is in mm.
For more details please refer the BS 1881-208.
Also, you can check these references..
https://www.icevirtuallibrary.com/doi/abs/10.1680/macr.1998.50.2.179
https://researchrepository.murdoch.edu.au/id/eprint/38133/1/initial-surface-absorption-test.pdf
https://publisher.uthm.edu.my/ojs/index.php/IJSCET/article/download/1495/1361/
Note: Above reference refer to the ISAT is a British Standard test designed to compare thoe water absorption poroperties of concretes in situ.
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